Draconic Ziggurat

The vast plains to the north of Bard's Gate hide many secrets that are just now being uncovered by the Wanderers. Ancient ziggurats marked with draconic imagery have recently had their secrets understood. Tool markings and structural sizes all indicate that these were human made, but they contain strong linguistical influences from draconic languages. Very few written records exist prior to the Hyperborean invasion and these give some glimpse into that period of history.
One by one, the ziggurats "activate", their walls glow softly and a hum is heard from the inside. The icongraphy inside shows a card game controlled by magic users. When enough cards are formed to create a deck they gain a sentience and will of their own. Though humans appear to be playing a game, it is the cards who trule control fate.
Images show decks of magic that are still around today, decks that retain their power and grant random effects based on randomly drawn cards. The Deck of Many is considered dangerous and to be used sparingly, though the rewards it offers can be great. This new discovery opens up a new understanding of their power.
Before the Wanderers even shared their discoveries, adventurers began assembling decks from found cards. They face off against others who have done the same and use these cards to gamble with one another. The winner does not receive gold, but a random card from his opponents deck.
Gamblers who gain more experience gain a greater understanding of their cards and can call upon their powers with much greater control. The need for more options, more power, has created illicit gambling bars beyond the control of guilds and governments alike. Factions have begun to form as certain groups are draw together by the guiding hand of these powerful cards.
Entry to deep parts require greater attunement to one's assembled deck so the knowledge contained in these ziggurats has only begun to be unraveled. The Wanderers even have difficulty maintaining the location of the ziggurats as they disappear and reappear at random. There may even only be one that merely presents different sides of itself. So much yet unknown but the first person to truly understand will be the bearer of great power.